Radiation effects on aryl glycosides. Part VII. Radiolysis of aqueous solutions of p-nitrophenyl β-D-glucopyranoside

Abstract

Pulse radiolysis experiments demonstrate that reactions of e_aq^–(k₂= 4 x 10¹⁰ I mol^–1) and OH (k₂= 2.1 x 10⁹ I mol^–1 s^–1) with p-nitrophenyl β-D-glucopyranoside (pNPG) yield transient species with absorption maxima near 300 nm. The results indicate that reactions occur mainly at the nitro-group. A transient species with absorption maximum at 450 nm in N₂O-saturated and in acidic solution is considered to be the nitrocyclohexadienyl radical. p-Nitrophenol, 4-nitrocatechol, glucose, 2-hydroxy-4-nitrophenyl β-D-glucopyranoside, and traces of αβ-unsaturated carbonyl compounds are produced during steady state ⁶⁰Co γ-irradiation of pNPG solutions, as a result of initial reaction of hydroxyl radicals. A mechanism is advanced for the formation of these products.